Munster maintained their stranglehold on top spot in the Magners League with a nail-biting 22-20 victory over the Glasgow Warriors at Musgrave Park on Saturday evening.

Colin Gregor dived over for a converted try just before the interval to help the visitors into a 10-3 half-time lead but Ronan O'Gara booted Munster into the lead with three penalties before David Wallace burrowed his way over just after the hour mark to put the hosts firmly in control.

However, Glasgow hit back almost right away through DTH van der Merwe and then Ruaridh Jackson slotted over a drop goal on 68 minutes to leave Munster facing the prospect of a first home defeat of the season.

There was to be late drama, though. Munster piled on the pressure in the closing stages and after Bernardo Stortoni had been yellow carded with just five minutes to play, O'Gara stepped up to stroke over his fifth penalty of the evening to nick it for the hosts.

Jackson's seventh-minute penalty opened the scoring after O'Gara had a kick charged down and John Hayes was pinged for not rolling away after a tackle.

Munster, who brought Denis Hurley in for the injured Doug Howlett (calf), mounted a swift response. Paul Warwick attacked with vigour and his kick forward was deflected into the path of Johne Murphy, who was brought to ground close to the Glasgow posts. Richie Gray killed the ball at the ensuing ruck and was promptly yellow carded. O'Gara tapped over the penalty to level the tie, but Munster could not make use of their numerical advantage.

Jackson missed a kickable penalty from the left, before Munster's forwards began to exert more influence on the half hour, and it took a terrific turnover from Ryan Grant to release the pressure.

Munster's frustration grew as infringements in the scrum and at the breakdown cost them valuable possession and territory, and Glasgow caught them off guard in the 37th minute.

Max Evans broke out of a double tackle near the Munster 22 and although Warwick caught up with him, his well-weighted pass inside was carried on by scrum half Gregor, whose fast feet saw him glide in behind the posts for a converted try.

On the stroke of half-time, Munster were pressing for a score when Keith Earls was very harshly sin-binned for not coming through the gate at a ruck.

Munster had got on the wrong side of referee James Jones in the opening half, but they quickly turned the 10-3 interval deficit around.

They stormed out of the blocks for the second half, with O'Gara landing a quick hat-trick of penalties. Referee Jones did little to help the game's flow, drawing the ire of the crowd on a number of occasions.

But he did well to spot Wallace's grounding for his 62nd-minute try, following a series of close range surges from his fellow forwards. O'Gara's conversion gave Munster some breathing space at 19-10.

However, Glasgow, hunting for their first away win of the season, had other ideas. Jackson was involved twice and Evans did brilliantly to pass out of the tackle, before the former unleashed van der Merwe for a 65th-minute score. Gregor stepped in to add the conversion and three minutes later, Jackson followed up with a tidy drop goal. A repeat of the Warriors' 2008 win at this venue was on the cards.

Yet Munster had time on their side and although their try-scoring attempts were thwarted - Stortoni saw yellow for deliberating knocking on, with the hosts about to convert an overlap - O'Gara landed his sixth successful kick from six attempts to keep his side on the winning trail.

The win keeps Munster nine points clear at the top of the table, while Glasgow, who watched Jackson miss a late, long range drop goal, slip to tenth.